initial.html
来自「jsf、swing的官方指南」· HTML 代码 · 共 388 行
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"><html> <head> <title>Initial Threads (The Java™ Tutorials > Creating a GUI with JFC/Swing > Concurrency in Swing)</title><style type="text/css"> .FigureCaption { margin-left: 1in; margin-right: 1in; font-family: sans-serif; font-size: smaller; text-align: justify; } #TopBar_bl { background: url(../../images/java_bar_bl.gif) 0 100% no-repeat; width: 100%; height: 60px; } #TopBar_br { background: url(../../images/java_bar_br.gif) 100% 100% no-repeat; width: 100%; height: 60px; } #TopBar_tl { background: url(../../images/java_bar_tl.gif) 0 0 no-repeat; width: 100%; height: 60px; } #TopBar_tr { background: url(../../images/java_bar_tr.gif) 100% 0 no-repeat; width: 100%; height: 60px; } #TopBar { background: #35556B url(../../images/java_bar.gif); margin: 10px 10px 0 10px; height:60px; min-width:700px; color: white; font-family: sans-serif; font-weight: bold; } @media print { #BreadCrumbs, #Download { display: none; } } #TopBar_right { line-height: 14px; 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var main = document.getElementById("MainFlow"); var toggle = document.getElementById("ToggleLeft"); if (b) { contents.className = "LeftBar_shown"; main.className = "MainFlow_indented"; toggle.innerHTML = "Hide the TOC"; document.cookie = 'tutorial_showLeftBar=yes; path=/'; } else { contents.className = "LeftBar_hidden"; main.className = "MainFlow_wide"; toggle.innerHTML = "Show the TOC"; document.cookie = 'tutorial_showLeftBar=no; path=/'; } } function toggleLeft() { showLeft(document.getElementById("LeftBar").className == "LeftBar_hidden"); document.getElementById("ToggleLeft").blur(); } function load() { showLeft(leftBar()); document.getElementById("ToggleLeft").style.display="inline"; } </script> </head><body onload="load()"> <div id=TopBar> <div id=TopBar_tr> <div id=TopBar_tl> <div id=TopBar_br> <div id=TopBar_bl> <div id=TopBar_right> <a target="_blank" href="http://java.sun.com/javase/6/download.jsp">Download the JDK</a> <br> <a href="../../search.html" target="_blank">Search the Tutorials</a> <br> <a href="javascript:toggleLeft()" id="ToggleLeft">Hide the TOC</a> </div> </div> </div> </div> </div> </div> <div class=PrintHeaders> <b>Trail:</b> Creating a GUI with JFC/Swing <br><b>Lesson:</b> Concurrency in Swing </div> <div id=LeftBar class=LeftBar_shown> <div id=Contents> <div class="linkLESSON"><a href="index.html">Concurrency in Swing</a></div><div class="nolinkAHEAD">Initial Threads</div><div class="linkAHEAD"><a href="dispatch.html">The Event Dispatch Thread</a></div><div class="linkAHEAD"><a href="worker.html">Worker Threads and SwingWorker</a></div><div class="linkBHEAD"><a href="simple.html">Simple Background Tasks</a></div><div class="linkBHEAD"><a href="interim.html">Tasks that Have Interim Results</a></div><div class="linkBHEAD"><a href="cancel.html">Canceling Background Tasks</a></div><div class="linkBHEAD"><a href="bound.html">Bound Properties and Status Methods</a></div></div> </div> <div id=MainFlow class=MainFlow_indented> <span id=BreadCrumbs> <a href=../../index.html target=_top>Home Page</a> > <a href=../index.html target=_top>Creating a GUI with JFC/Swing</a> > <a href=index.html target=_top>Concurrency in Swing</a> </span> <div class=NavBit> <a target=_top href=index.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=dispatch.html>Next »</a> </div> <div id=PageTitle>Initial Threads</div> <blockquote>Every program has a set of threads where the application logic begins.In standard programs, there's only one such thread: the thread thatinvokes the <code>main</code> method of the program class. In appletsthe initial threads are the ones that construct the applet object andinvoke its <code>init</code> and <code>start</code> methods; theseactions may occur on a single thread, or on two or three differentthreads, depending on the Java platform implementation. In thislesson, we call these threads the <i>initial threads</i>.<p>In Swing programs, the initial threads don't have a lot to do. Theirmost essential job is to create a <code>Runnable</code> object thatinitializes the GUI and schedule that object for execution on theevent dispatch thread. Once the GUI is created, the program isprimarily driven by GUI events, each of which causes the execution ofa short task on the event dispatch thread. Application code canschedule additionals tasks on the event dispatch thread (if theycomplete quickly, so as not to interfere with event processing) or aworker thread (for long-running tasks).<p>An initial thread schedules the GUI creation task by invoking<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SwingUtilities.html#invokeLater(java.lang.Runnable)"><code>javax.swing.SwingUtilities.invokeLater</code></a>or<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SwingUtilities.html#invokeAndWait(java.lang.Runnable)"><code>javax.swing.SwingUtilities.invokeAndWait</code></a>. Both of these methods take a single argument: the<code>Runnable</code> that defines the new task. Their only differenceis indicated by their names: <code>invokeLater</code> simply schedulesthe task and returns; <code>invokeAndWait</code> waits for the task tofinish before returning.<p>You can see examples of this throughout the Swing tutorial:<blockquote><pre>SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); }}</pre></blockquote>In an applet, the GUI-creation task must be launched from the<code>init</code> method using <code>invokeAndWait</code>; otherwise,<code>init</code> may return before the GUI is created, which maycause problems for a web browser launching an applet. In any otherkind of program, scheduling the GUI-creation task is usually the lastthing the initial thread does, so it doesn't matter whether ituses <code>invokeLater</code> or <code>invokeAndWait</code>.<p>Why doesn't the initial thread simply create the GUI itself? Becausealmost all code that creates or interacts with Swing components mustrun on the event dispatch thread. This restriction is discussedfurther in the next section. </blockquote> <div class=NavBit> <a target=_top href=index.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=dispatch.html>Next »</a> </div> </div> <div id=Footer><div id=TagNotes> Problems with the examples? Try <a target="_blank" href=../../information/run-examples.html>Compiling and Running the Examples: FAQs</a>. <br> Complaints? Compliments? Suggestions? <a target="_blank" href="http://developer.sun.com/contact/tutorial_feedback.jsp">Give us your feedback</a>.<br><br> <a target="_blank" href="../../information/copyright.html">Copyright</a> 1995-2006 Sun Microsystems, Inc. All rights reserved. <span id=Download></span></div> </div> <div class=PrintHeaders> <b>Previous page:</b> Concurrency in Swing <br><b>Next page:</b> The Event Dispatch Thread </div> </body></html> ⌨️ 快捷键说明
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